We highly recommend Wimonpak's apartment! This was one of our favorite airbnbs that we've stayed in, and it made our time in Bangkok very enjoyable. The room is nice and clean, the cable entertaining, and the WiFi very fast! The bed was one of the most comfortable we've had at an airbnb in this price range. The shower has nice, warm water and and the kitchenette was a great touch. In particular, we really loved the sandwich maker/toaster!
Location is also perfect. Even in 30C weather, it was an easy walk to the sky train. You're away from the craziness of Khao San, but getting there is a short, cheap, water taxi ride if you feel so inclined. We highly recommend this listing!